Validate that the verify function checks the signature length

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>

Author: gilles-peskine-arm

tests/suites/test_suite_pqcp_mldsa.function

@@ -139,23 +139,53 @@ exit:
 /* BEGIN_CASE depends_on:TF_PSA_CRYPTO_PQCP_MLDSA_87_ENABLED */
 void verify_pure_87(data_t *public_key, data_t *message, data_t *signature)
 {
+    size_t candidate_size = signature->len;
+    uint8_t *candidate = NULL;
+
     /* Sanity checks on the test data that we pass to the function under test */
     TEST_EQUAL(public_key->len, MLDSA_PUBLICKEYBYTES(87));
     TEST_EQUAL(signature->len, MLDSA_BYTES(87));
 
     /* Verify the signature */
-    TEST_EQUAL(tf_psa_crypto_pqcp_mldsa87_verify(signature->x, signature->len,
+    TEST_CALLOC(candidate, candidate_size);
+    memcpy(candidate, signature->x, signature->len);
+    TEST_EQUAL(tf_psa_crypto_pqcp_mldsa87_verify(candidate, candidate_size,
                                                  message->x, message->len,
                                                  NULL, 0,
                                                  public_key->x), 0);
 
     /* Verify that a one-bit-off signature is wrong */
-    signature->x[signature->len - 1] ^= 1;
-    TEST_EQUAL(tf_psa_crypto_pqcp_mldsa87_verify(signature->x, signature->len,
+    candidate[candidate_size - 1] ^= 1;
+    TEST_EQUAL(tf_psa_crypto_pqcp_mldsa87_verify(candidate, candidate_size,
+                                                 message->x, message->len,
+                                                 NULL, 0,
+                                                 public_key->x), MLD_ERR_FAIL);
+    mbedtls_free(candidate);
+    candidate = NULL;
+
+    /* Verify that a shorter signature is rejected */
+    candidate_size = signature->len - 1;
+    TEST_CALLOC(candidate, candidate_size);
+    memcpy(candidate, signature->x, signature->len - 1);
+    TEST_EQUAL(tf_psa_crypto_pqcp_mldsa87_verify(candidate, candidate_size,
                                                  message->x, message->len,
                                                  NULL, 0,
                                                  public_key->x), MLD_ERR_FAIL);
-    signature->x[signature->len - 1] ^= 1;
+    mbedtls_free(candidate);
+    candidate = NULL;
+
+    /* Verify that a longer signature is rejected */
+    candidate_size = signature->len + 1;
+    TEST_CALLOC(candidate, candidate_size);
+    memcpy(candidate, signature->x, signature->len);
+    TEST_EQUAL(tf_psa_crypto_pqcp_mldsa87_verify(candidate, candidate_size,
+                                                 message->x, message->len,
+                                                 NULL, 0,
+                                                 public_key->x), MLD_ERR_FAIL);
+    mbedtls_free(candidate);
+    candidate = NULL;
 
+exit:
+    mbedtls_free(candidate);
 }
 /* END_CASE */